This protocol will develop behavioral methods of preventing the health risks of long sleep. Prospective data indicate that 5 percent of population mortality is associated with long sleep (or perhaps long time-in-bed), specifically, reported sleep durations of > 7.5 hours per night. Long sleep durations are particularly prevalent in older adults, who tend to spend more time in bed, despite reduced total sleep time compared with younger adults. Moderate sleep restriction might, therefore, be one of the simplest and most effective means of prolonging life, as well as consolidating sleep. Strong support for this hypothesis can only be established with randomized long-term sleep restriction of thousands of people. Before such research can be justified, the safety and feasibility of sleep restriction in long sleepers must be demonstrated. The proposed study will examine whether older long sleepers are able to chronically restrict time-in-bed without suffering potential negative consequences. Fifty adults ages 50-70 yrs who report normally sleeping > 8.5 hrs will be examined. Following a two-week home baseline period, volunteers will be randomly assigned to two 8-week home treatments. A sleep restriction group (n=30) will follow a fixed sleep schedule in which time-in-bed is restricted precisely 90 min below each subject's median baseline time-in-bed. A control group (n=20) will have no sleep restriction, but will follow a fixed sleep schedule consistent with each subject's median baseline schedule. Adherence to the protocols will be assessed by examining the number of days in which the volunteers remain in the study, as well as changes in time-in-bed and estimated sleep. Benefits and risks will be assessed by examining changes in sleepiness, depression, quality-of-life, neurobehavioral performance, glucose tolerance, and actigraphic and subjective sleep. [unreadable] [unreadable]